Technical Field
The invention generally relates to the signaling of resource allocation information to a terminal of a mobile communication system for assigning resources to the terminal. In particular, the invention relates to the signaling of resource allocations using downlink control information for single-cluster and multi-cluster allocations in 3GPP LTE or 3GPP LTE-A. More specifically, one aspect of the invention provides a concept for signaling resource allocation information for cases where the number of available bits within the downlink control information is insufficient to represent all possible resource allocations that are supported by the system, for example, all allowed combinations of single-cluster or multi-cluster allocations. In principle, the disclosed invention can be applied to the signaling of uplink resource allocation information and downlink resource allocation information, while additional advantages are achieved with regard to certain configuration of uplink resource allocations in 3GPP LTE or 3GPP LTE-A.
Description of the Related Art
In mobile communication systems, a base station assigns downlink resources to a terminal, which the base station can use for downlink transmissions to said terminal, and/or assigns uplink resources to a terminal, which said terminal can use for uplink transmissions. The downlink and/or uplink resource allocation (or assignment) is signaled from the base station (or another related network device) to the terminal. The downlink and/or uplink resource allocation information is typically signaled as part of a downlink control information having multiple predefined flags and/or predefined fields, one of which being a field dedicated for signaling the resource allocation information.
Typically, the available number of bits that can be used to signal the resource assignment information to the terminals is predetermined by a technical specification. For example, technical specification defines the size and format of the downlink control information within which the resource assignment information is transmitted to the terminals.
Likewise, the resource allocations, or the size of the resource allocations are predetermined by a technical specification. Moreover, assignment of the uplink or downlink resources to the terminals is typically defined and given by a technical specification. For example, the uplink resources can be expressed as resource blocks, meaning that the granularity on which a user or terminal can be allocated uplink resources is the number and the position of the assignable uplink resource blocks. In this case, the technical specification typically defines the allowed combinations of resource blocks that are supported by the mobile communication system. Since the allowed resource allocations, the size of the resource allocations or the supported combinations of assignable resources are defined or predetermined, the number of bits that is required to denote all supported (combinations of) resource(s) is effectively given.
Therefore, neither the available number of bits that can be used to signal the resource assignment information nor the required number bits to denote the supported (combinations of) resource(s) can freely be chosen.
The present invention has recognized that situations can occur, in which the number of bits that is available for signaling the resource assignment information is insufficient to represent all possible resource assignments that are supported by the communication system.
The general concepts of the invention are described below in regard to 3GPP LTE and LTE-A communication systems and particularly for multiple cluster allocations specified in 3GPP LTE(-A). However, it is to be understood that the reference to 3GPP LTE and LTE-A is only an example according to specific embodiments of the invention but the general concepts of the invention can be applied to different resource allocation processes of different communication systems.
The disclosed embodiments of the invention for signaling uplink resource information to a terminal can be applied to the signaling of downlink resource information without departing from the invention. For example, the downlink resources according to LTE(-A) are assigned by the scheduler as resource blocks (RB) as the smallest possible unit of resources. The downlink component carrier (or cell) is subdivided in the time-frequency domain in sub-frames, which are each divided into two downlink slots for signaling control channel region (PDCCH region) and OFDM symbols. As such, the resource grid as illustrated in FIG. 3 for uplink resources in LTE(-A) has the same structure for downlink resources. Therefore, the signaling of allocated downlink resources with fewer bits that would be required to express all allowed resource block allocations that are supported by the communication system can be achieved in the same manner as suggested herein with regard to downlink resources.
Moreover, the terms “resource assignment” and “resource allocation” are used in this specification to denote both the same technical meaning of assigning or allocating resources. Both terms are therefore interchangeable without any change in content and technical meaning.
Long Term Evolution (LTE)
Third-generation mobile systems (3G) based on WCDMA radio-access technology are deployed on a broad scale all around the world. A first step in enhancing or evolving this technology entails introducing High-Speed Downlink Packet Access (HSDPA) and an enhanced uplink, also referred to as High Speed Uplink Packet Access (HSUPA), giving a radio-access technology that is highly competitive.
In order to be prepared for further increasing user demands and to be competitive against new radio access technologies 3GPP introduced a mobile communication system called Long Term Evolution (LTE). LTE is designed to meet the carrier needs for high speed data and media transport as well as high capacity voice support to the next decade. The ability to provide high bit rates is a key measure for LTE.
The work item (WI) specification on Long-Term Evolution (LTE) called Evolved UMTS Terrestrial Radio Access (UTRA) and UMTS Terrestrial Radio Access Network (UTRAN) is finalized as Release 8 (LTE). The LTE system represents efficient packet-based radio access and radio access networks that provide full IP-based functionalities with low latency and low cost. According to LTE, scalable multiple transmission bandwidths are specified such as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz, in order to achieve flexible system deployment using a given spectrum. In the downlink, Orthogonal Frequency Division Multiplexing (OFDM) based radio access was adopted due to its inherent immunity to multipath interference (MPI) caused by a low symbol rate, the use of a cyclic prefix (CP), and its affinity to different transmission bandwidth arrangements. Single-Carrier Frequency Division Multiple Access (SC-FDMA) based radio access was adopted in the uplink, since provisioning of wide area coverage was prioritized over improvement in the peak data rate considering the restricted transmission power of the user equipment (UE). Many key packet radio access techniques are employed including multiple-input multiple-output (MIMO) channel transmission techniques, and a highly efficient control signaling structure is achieved in LTE (for example, Release 8).
LTE Architecture
The overall architecture of a communication system according to LTE(-A) shown in FIG. 1. A more detailed representation of the E-UTRAN architecture is given in FIG. 2.
The E-UTRAN comprises an eNodeB that provides the E-UTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the user equipment (UE). The eNodeB (eNB) hosts the Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Control Protocol (PDCP) layers that include the functionality of user-plane header-compression and encryption. It also offers Radio Resource Control (RRC) functionality corresponding to the control plane. It performs many functions including radio resource management, admission control, scheduling, enforcement of negotiated uplink Quality of Service (QoS), cell information broadcast, ciphering/deciphering of user and control plane data, and compression/decompression of downlink/uplink user plane packet headers. The eNodeBs are interconnected with each other by means of the X2 interface.
The eNodeBs are further connected by means of the S1 interface to the EPC (Evolved Packet Core). More specifically, eNodeBs are connected to the MME (Mobility Management Entity) by means of the S1-MME and to the Serving Gateway (SGW) by means of the S1-U. The S1 interface supports a many-to-many relation between MMEs/Serving Gateways and eNodeBs. The SGW routes and forwards user data packets, while also acting as the mobility anchor for the user plane during inter-eNodeB handovers and as the anchor for mobility between LTE and other 3GPP technologies (terminating S4 interface and relaying the traffic between 2G/3G systems and PDN GW). For idle state user equipments, the SGW terminates the downlink data path and triggers paging when downlink data arrives for the user equipment. It manages and stores user equipment contexts, e.g., parameters of the IP bearer service, network internal routing information. It also performs replication of the user traffic in case of lawful interception.
The MME is the key control-node for the LTE access-network. It is responsible for idle mode user equipment tracking and paging procedure including retransmissions. It is involved in the bearer activation/deactivation process and is also responsible for choosing the SGW for a user equipment at the initial attach time and at the time of intra-LTE handover involving Core Network (CN) node relocation. It is responsible for authenticating the user (by interacting with the HSS). The Non-Access Stratum (NAS) signaling terminates at the MME and it is also responsible for generation and allocation of temporary identities to user equipments. It checks the authorization of the user equipment to camp on the service provider's Public Land Mobile Network (PLMN) and enforces user equipment roaming restrictions. The MME is the termination point in the network for ciphering/integrity protection for NAS signaling and handles the security key management. Lawful interception of signaling is also supported by the MME. The MME also provides the control plane function for mobility between LTE and 2G/3G access networks with the S3 interface terminating at the MME from the SGSN. The MME also terminates the S6a interface towards the home HSS for roaming user equipments.
Component Carrier Structure in LTE
The downlink component carrier of a 3GPP LTE (such as Release 8) is subdivided in the time-frequency domain in so-called sub-frames. In 3GPP LTE each sub-frame is divided into two downlink slots as illustrated in FIG. 3, wherein the first downlink slot comprises the control channel region (PDCCH region) within the first OFDM symbols. Each sub-frame consists of a given number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE Release 8), wherein each of OFDM symbol spans over the entire bandwidth of the component carrier. Thus, each OFDM symbol consists of a number of modulation symbols transmitted on respective NRBDL×NscRB subcarriers as also shown in FIG. 4.
Assuming a multi-carrier communication system, e.g., employing OFDM, as for example used in 3GPP Long Term Evolution (LTE), the smallest unit of resources that can be assigned by the scheduler is one “resource block”. A physical resource block is defined as NsymbDL, consecutive OFDM symbols in the time domain and NscRB consecutive subcarriers in the frequency domain as illustrated in FIG. 4. In 3GPP LTE (such as Release 8), a downlink physical resource block thus consists of NsymbDL×NscRB resource elements, corresponding to one slot in the time domain and 180 kHz in the frequency domain. Further details on the downlink resource grid can be obtained, for example, from 3GPP TS 36.211, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, version 8.9.0 or 9.0.0, section 6.2, available at http://www.3gpp.org and incorporated herein by reference. Likewise, the sub-frame structure on a downlink component carrier and the downlink resource grid illustrated in FIGS. 3 and 4 are obtained from 3GPP TS 36.211.
For the LTE uplink resource allocation, the structure of the resource blocks is comparable to the above structure of the downlink resource grid. For the uplink resources, each OFDM symbol consists of a number of modulation symbols transmitted on respective NRBUL×NscRB subcarriers as also shown in FIG. 5. The exemplary structure of an uplink resource grid illustrated in FIG. 5 corresponds to the structure of the exemplary downlink resource grid illustrated in FIG. 4. The exemplary uplink resource grid of FIG. 4 is obtained from 3GPP TS 36.211 V10.0.0, which is incorporated herein by reference and provides further details of the uplink resources in LTE (Release 10).
L1/L2 Control Signaling—Downlink Control Information in LTE(-A)
In order to inform a scheduled user or terminal about their allocation status, transport format and other data related information (e.g., HARQ information), L1/L2 (Layer1/Layer2) control signaling is transmitted on the downlink along with the data. L1/L2 control signaling is multiplexed with the downlink data in a sub-frame, assuming that the user allocation can change from sub-frame to sub-frame. It should be noted that user allocation might also be performed on a TTI (Transmission Time Interval) basis, where the TTI length is a multiple of the sub-frames. The TTI length may be fixed in a service area for all users, may be different for different users, or may even by dynamic for each user. Generally, the L1/2 control signaling needs only be transmitted once per TTI. The L1/L2 control signaling is transmitted on the Physical Downlink Control Channel (PDCCH). It should be noted that in 3GPP LTE, assignments for uplink data transmissions, also referred to as uplink scheduling grants or uplink resource assignments, are also transmitted on the PDCCH.
Generally, the information sent on the L1/L2 control signaling (particularly LTE(-A) Release 10) can be categorized to the following items:                User identity, indicating the user that is allocated. This is typically included in the checksum by masking the CRC with the user identity;        Resource allocation information, indicating the resources (Resource Blocks, RBs) on which a user is allocated. Note, that the number of RBs on which a user is allocated can be dynamic;        Carrier indicator, which is used if a control channel transmitted on a first carrier assigns resources that concern a second carrier, i.e., resources on a second carrier or resources related to a second carrier;        Modulation and coding scheme that determines the employed modulation scheme and coding rate;        HARQ information, such as a new data indicator (NDI) and/or a redundancy version (RV) that is particularly useful in retransmissions of data packets or parts thereof;        Power control commands to adjust the transmit power of the assigned uplink data or control information transmission;        Reference signal information such as the applied cyclic shift and/or orthogonal cover code index, which are to be employed for transmission or reception of reference signals related to the assignment;        Uplink or downlink assignment index that is used to identify an order of assignments, which is particularly useful in TDD systems;        Hopping information, e.g., an indication whether and how to apply resource hopping in order to increase the frequency diversity;        CQI request, which is used to trigger the transmission of channel state information in an assigned resource; and        Multi-cluster information, which is a flag used to indicate and control whether the transmission occurs in a single cluster (contiguous set of RBs) or in multiple clusters (at least two non-contiguous sets of contiguous RBs). Multi-cluster allocation has been introduced by 3GPP LTE-(A) Release 10.        
It is to be noted that the above listing is non-exhaustive, and not all mentioned information items need to be present in each PDCCH transmission depending on the DCI format that is used.
DCI occurs in several formats that differ in their overall size and the field information that is used. The different DCI formats that are currently defined for LTE(-A) Release 10 are described in detail in TS 36.212 v10.0.0 in section 5.3.3.1, available at http://www.3gpp.org and incorporated herein by reference.
The following two specific DCI formats defined in LTE show exemplarily some of the functionality of the various DCI formats:                DCI format 0 is used for the scheduling of the PUSCH (Physical Uplink Shared Channel) using single-antenna port transmissions in uplink transmission mode 1 or 2,        DCI format 4 is used for the scheduling of the PUSCH (Physical Uplink Shared Channel) using closed-loop spatial multiplexing transmissions in uplink transmission mode 2.        
Uplink transmission modes 1 and 2 are defined in TS 36.213 v10.0.1 in section 8.0, the single-antenna port is defined in section 8.0.1, and the closed-loop spatial multiplexing is defined in section 8.0.2, which are available at http://www.3gpp.org and incorporated herein by reference.
There are several different ways how to exactly transmit the information pieces mentioned above. Moreover, the L1/L2 control information may also contain additional information or may omit some of the information, such as:                the HARQ process number may not be needed in case of a synchronous HARQ protocol, as, for example, used in uplink,        Spatial-multiplexing related control information, such as, for example, precoding, may be additionally included in the control signaling, or        In case of multi-code word spatial multiplexing transmission, the MCS and/or HARQ information for multiple code words may be included.        
For uplink resource assignments (e.g., concerning the Physical Uplink Shared Channel, PUSCH) signaled on PDCCH (Physical Downlink Control Channel) in LTE, the L1/L2 control information does not contain a HARQ process number, since a synchronous HARQ protocol is employed for LTE uplink transmissions. The HARQ process to be used for an uplink transmission is determined and given by the specified timing. Furthermore, it is to be noted that the redundancy version (RV) information and the MCS information are jointly encoded.
Downlink & Uplink Data Transmissions in LTE(-A)
This section provides further background on downlink and uplink data transmissions according to the technical specification of LTE(-A) that may be useful to comprehend the background, framework and full usability of the subsequently discussed embodiments of the invention. This section therefore provides only illustrative information concerning background information, a person skilled in the field of the invention will consider as common knowledge.
Regarding downlink data transmission in LTE, L1/L2 control signaling is transmitted on a separate physical channel (PDCCH), along with the downlink packet data transmission. This L1/L2 control signaling typically contains information on:                The physical resource(s) on which the data is transmitted (e.g., subcarriers or subcarrier blocks in case of OFDM, codes in case of CDMA). This information allows the UE (receiver) to identify the resources on which the data is transmitted.        When user equipment is configured to have a Carrier Indication Field (CIF) in the L1/L2 control signaling this information identifies the component carrier for which the specific control signaling information is intended. This enables assignments to be sent on one component carrier which are intended for another component carrier (“cross-carrier scheduling”). This other, cross-scheduled component carrier could be for example a PDCCH-less component carrier, i.e., the cross-scheduled component carrier does not carry any L1/L2 control signaling.        The Transport Format, which is used for the transmission. This can be the transport block size of the data (payload size, information bits size), the MCS (Modulation and Coding Scheme) level, the Spectral Efficiency, the code rate, etc. This information (usually together with the resource allocation (e.g., the number of resource blocks assigned to the user equipment)) allows the user equipment (receiver) to identify the information bit size, the modulation scheme and the code rate in order to start the demodulation, the de-rate-matching and the decoding process. The modulation scheme may be signaled explicitly.        Hybrid ARQ (HARQ) information:                    HARQ process number: Allows the user equipment to identify the hybrid ARQ process on which the data is mapped.            Sequence number or new data indicator (NDI): Allows the user equipment to identify if the transmission is a new packet or a retransmitted packet. If soft combining is implemented in the HARQ protocol, the sequence number or new data indicator together with the HARQ process number enables soft-combining of the transmissions for a PDU prior to decoding.            Redundancy and/or constellation version: Tells the user equipment, which hybrid ARQ redundancy version is used (required for de-rate-matching) and/or which modulation constellation version is used (required for demodulation).                        UE Identity (UE ID): Tells for which user equipment the L1/L2 control signaling is intended for. In typical implementations this information is used to mask the CRC of the L1/L2 control signaling in order to prevent other user equipments to read this information.        
To enable an uplink packet data transmission in LTE, L1/L2 control signaling is transmitted on the downlink (PDCCH) to tell the user equipment about the transmission details. This L1/L2 control signaling typically contains information on:                The physical resource(s) on which the user equipment should transmit the data (e.g., subcarriers or subcarrier blocks in case of OFDM, codes in case of CDMA).        When user equipment is configured to have a Carrier Indication Field (CIF) in the L1/L2 control signaling this information identifies the component carrier for which the specific control signaling information is intended. This enables assignments to be sent on one component carrier which are intended for another component carrier. This other, cross-scheduled component carrier may be for example a PDCCH-less component carrier, i.e., the cross-scheduled component carrier does not carry any L1/L2 control signaling.        L1/L2 control signaling for uplink grants is sent on the DL component carrier that is linked with the uplink component carrier or on one of the several DL component carriers, if several DL component carriers link to the same UL component carrier.        The Transport Format, the user equipment should use for the transmission. This can be the transport block size of the data (payload size, information bits size), the MCS (Modulation and Coding Scheme) level, the Spectral Efficiency, the code rate, etc. This information (usually together with the resource allocation (e.g., the number of resource blocks assigned to the user equipment)) allows the user equipment (transmitter) to pick the information bit size, the modulation scheme and the code rate in order to start the modulation, the rate-matching and the encoding process. In some cases the modulation scheme maybe signaled explicitly.        Hybrid ARQ information:                    HARQ Process number: Tells the user equipment from which hybrid ARQ process it should pick the data.            Sequence number or new data indicator: Tells the user equipment to transmit a new packet or to retransmit a packet. If soft combining is implemented in the HARQ protocol, the sequence number or new data indicator together with the HARQ process number enables soft-combining of the transmissions for a protocol data unit (PDU) prior to decoding.            Redundancy and/or constellation version: Tells the user equipment, which hybrid ARQ redundancy version to use (required for rate-matching) and/or which modulation constellation version to use (required for modulation).                        UE Identity (UE ID): Tells which user equipment should transmit data. In typical implementations this information is used to mask the CRC of the L1/L2 control signaling in order to prevent other user equipments to read this information.        
There are several different available ways of how to exactly transmit the information pieces mentioned above in uplink and downlink data transmission in LTE. Moreover, in uplink and downlink, the L1/L2 control information may also contain additional information or may omit some of the information. For example:                HARQ process number may not be needed, i.e., is not signaled, in case of a synchronous HARQ protocol.        A redundancy and/or constellation version may not be needed, and thus not signaled, if Chase Combining is used (always the same redundancy and/or constellation version) or if the sequence of redundancy and/or constellation versions is pre-defined.        Power control information may be additionally included in the control signaling.        MIMO related control information, such as, e.g., pre-coding, may be additionally included in the control signaling.        In case of multi-code word MIMO transmission transport format and/or HARQ information for multiple code words may be included.        
For uplink resource assignments (on the Physical Uplink Shared Channel (PUSCH)) signaled on PDCCH in LTE, the L1/L2 control information does not contain a HARQ process number, since a synchronous HARQ protocol is employed for LTE uplink. The HARQ process to be used for an uplink transmission is given by the timing. Furthermore it should be noted that the redundancy version (RV) information is jointly encoded with the transport format information, i.e., the RV info is embedded in the transport format (TF) field. The Transport Format (TF) respectively modulation and coding scheme (MCS) field has for example a size of 5 bits, which corresponds to 32 entries. 3 TF/MCS table entries are reserved for indicating redundancy versions (RVs) 1, 2 or 3. The remaining MCS table entries are used to signal the MCS level (TBS) implicitly indicating RV0. The size of the CRC field of the PDCCH is 16 bits.
For downlink assignments (PDSCH) signaled on PDCCH in LTE the Redundancy Version (RV) is signaled separately in a two-bit field. Furthermore the modulation order information is jointly encoded with the transport format information. Similar to the uplink case there is 5 bit MCS field signaled on PDCCH. 3 of the entries are reserved to signal an explicit modulation order, providing no Transport format (Transport block) info. For the remaining 29 entries modulation order and Transport block size info are signaled.
Resource Allocation Fields for Uplink Resource Assignments
According to 3GPP TS 36.212 v10.0.0, the DCI formats 0 can, for example, be used for uplink resources assignments. The DCI formats 0 contains—amongst others—a so-called “resource block assignment and hopping resource allocation” field, which has a size of ┌log2(NRBUL(NRBUL+1)/2)┐ bits, where NRBUL denotes the number of resource blocks in the uplink.
LTE-(A) presently foresees three possible uplink resource allocation schemes, which are single-cluster allocation with non-hopping PUSCH (Physical Uplink Shared channel), single-cluster allocation with hopping PUSCH and multi-cluster allocation. Multi-cluster allocation is introduced in Release 10 and is only supported as with non-hopping PUSCH.
In case of a single-cluster allocation with non-hopping PUSCH, the entire “resource block assignment and hopping resource allocation” field of the DCI is used to signal the resource allocation in the uplink sub-frame.
In case of a single-cluster allocation with hopping PUSCH, the NUL_hop MSB (most significant bits) of the field are used to specify the detailed hopping configuration, while the remainder of the field provides the resource allocation in the first slot in the uplink sub-frame. NUL_hop can thereby be determined from the system bandwidth according to table 1. Table 1 is obtained from table 8.4-1 of 3GPP TS 36.213 v10.0.1, which is incorporated herein by reference. The system bandwidth NRBUL denotes the number of uplink physical resource blocks.
TABLE 1Number of HoppingSystembits for second slotBandwidthRANRBULNUL—hop6-49150-1102
In case of a multi-cluster allocation with non-hopping PUSCH, the uplink resource allocation is signaled using the concatenation of the frequency hopping flag field and the resource block assignment and hopping resource allocation field of the DCI.
The case of multi-cluster allocation with hopping PUSCH is not defined in LTE. For this reason, the frequency hopping flag field (as required for single-cluster allocation) can be used for signaling uplink resource allocation in case of multi-cluster allocation.
For multi-cluster allocations,
  ⌈            log      2        ⁡          (              (                                                            ⌈                                                                            N                      RB                      UL                                        /                    P                                    +                  1                                ⌉                                                                        4                                      )            )        ⌉bits are required to denote or specify all allowed and supported combinations. According to 3GPP LTE(-A) multi-cluster allocation, the smallest unit of uplink resources that can be assigned is one “resource block group” (RBG) as outlined below in more details.
The size of the RBG can be determined from the system bandwidth according to table 2. Table 2 is obtained from table 7.1.6.1-1 of 3GPP TS 36.213 v10.0.1 by replacing NRBDL with NRBUL accordingly. The system bandwidth NRBUL denotes the number of uplink physical resource blocks.
TABLE 2SystemBandwidthRBG SizeNRBUL(P)≦10111-26227-633 64-1104Multi-Cluster Allocation Interpretation
As mentioned above, hopping is not supported for LTE multi-cluster RBA. The hopping flag of the DCI is therefore prepended to the RBA field, which increases the size by 1 bit. While for single-cluster the allocation is based on a resource-block granularity, for multi-cluster allocations the granularity is based on a resource block group (RBG). An RBG is the union of P adjacent RBs, where P can be established using Table 2 for any uplink system bandwidth supported by LTE. The only exception is the case where NRBUL is not an integer multiple of P, and where therefore the last RBG contains the remaining RBs. Each RB is part of only one RBG. The number of uplink RBGs NRBGUL can then be computed as
      N    RBG    UL    =            ⌈                        N          RB          UL                P            ⌉        .  
As multi-cluster allocation is known and defined in 3GPP LTE Release 10, further details of the RBGs and the allowed combination of RBs (which form the RBGs) that are supported by the system are not required and therefore omitted. The multi-cluster allocation according to 3GPP LTE Release 10 and specifically the DCI format 0 for signaling the multi-cluster resource allocation as defined in 3GPP TS 36.212 V10.0.0 is incorporated herein by reference.
According to 3GPP LTE Release 10, multi-cluster allocations are restricted to support only two clusters, where the first cluster is identified by the starting RBG s0 and ending RBG s1−1 and where the second cluster is identified by the starting RBG s2 and ending RBG s3−1. These four parameters are then linked into a single value r which represents the multi-cluster allocation by the following formula:
      r    =                  〈                                                            N                -                                  s                  0                                                                                        M                                      〉            +              〈                                                            N                -                                  s                  1                                                                                                        M                -                1                                                    〉            +              〈                                                            N                -                                  s                  2                                                                                                        M                -                2                                                    〉            +              〈                                                            N                -                                  s                  3                                                                                                        M                -                3                                                    〉              ,where M=4 (corresponding the four starting and ending RBGs that define a multi-cluster consisting of two clusters), N=NRBGUL+1 and 1≦s0<s1<s2<s3≦N, and where
      〈                            x                                      y                      〉    =      {                                                                      (                                                                            x                                                                                                  y                                                                      )                            =                                                x                  !                                                                      y                    !                                    ·                                      (                                          x                      -                                              y                        ⁢                                                  )!                                                                                                                                                                            x              ≥              y                                                            0                                              x              <              y                                          .      
Furthermore, 3GPP LTE Release 10 requires that the two clusters are non-adjacent, i.e., there is a spacing of at least one RBG between the end of the first cluster and the start of the second cluster. This conditions leads to the above formula and the inequality relations between values s0, s1, s2, s3.
The present invention has recognized that for most cases (i.e., for most values of the uplink system bandwidth define by the specification 3GPP TS 36.213), the number of available bits in the DCI and required bits to denote all allowed RBG allocation combinations supported by the system are matching. However, for some cases an insufficient number of bits is available in the DCI as outlined above.